Conventionally, there has been known a control device for hybrid vehicle drive apparatus including a differential mechanism having a first rotary element connected to an internal combustion engine, a second electric motor connected to a first electric motor, and a third rotary element connected to a second electric motor and a power transmitting path. For instance, Patent Publication 1 (Japanese Patent Application Publication No. 2005-264762) discloses such a control device for hybrid vehicle drive apparatus. The control device for hybrid vehicle drive apparatus was arranged to execute a motor drive running mode to cause a vehicle to run using an output of the second electric motor, with the internal combustion engine remaining in a halted condition.
During the motor drive running mode, the internal combustion engine encountered running vibrations resulting from the running of the vehicle when the internal combustion engine remains in the halted condition. In such a case, more particularly, component parts of the internal combustion engine continuously remained in contact with each other with the same attitudes and no lubricating oil circulated in the internal combustion engine. If such a condition continuously occurred, it was considered that the running vibrations gave adverse affect on durability of the internal combustion engine.
However, despite the control device for hybrid vehicle drive apparatus disclosed in Patent Publication 1 enabling the initiation of the motor drive running mode, no consideration has been taken on the running vibrations possibly causing an adverse affect on the internal combustion engine remaining halted during the motor drive running mode.